Portable speaker system



FIG. 1 is front-top-left perspective view of a portable speaker system showing our new design;

FIG. 2 is a front view thereof;

FIG. 3 is a back view thereof;

FIG. 4 is a left side view thereof;

FIG. 5 is a right side view thereof;

FIG. 6 is a top view thereof; and,

FIG. 7 is a bottom view thereof.

The broken lines showing of the unclaimed environment forms no part of the claimed design. 

The ornamental design for a portable speaker system, as shown and described. 